With the single stage RCBS press, would it be to my advanage to get two, one for decapping/sizeing and one for seating the bullet? Would this speed up the process? Or just changing the two dies on one press is the way to go?

Again, will be loading 22-250, 243, and 308's.

Also, I understand to get the correct OAL for my gun, I will barely seat a bullet in the case, then put it my rifle and lock the bolt. I remove the bullet, measure it, and subtract .002 to have the exact OAL for my gun? Is this correct? I will have to do this with every gun as I have three 308's.